1. Field of the Invention
The field of the invention relates to multi-component load transducers utilizing multiple strain gage load channels for precise measurement of forces and moments and, more particularly, to beam-style load cells requiring an overall small size, high capacity, and yet high sensitivity.
2. Background and Related Art
The use of strain gages in load transducers to measure forces and moments is a known art. A transducer can incorporate one or more load channels. Each load channel measures one of the load components, and is comprised of one or more strain gages mounted to one or more elastic elements that deform under the applied load. An appropriate circuitry relates the resistance change in each set of gages to the applied force or moment. Strain gages have many industrial, medical, and electrical applications due to their small size, low production cost, flexibility in installation and use, and high precision.
A typical low profile, small, multi-component load transducer only functions correctly when the axial (i.e. vertical) force acts relatively central to the transducer. Specifications of such transducers indicate a maximum allowable offset for the force being approximately half the diameter of the transducer. Technical specifications of transducers are given as the allowable force and moment ratings, where the moment rating is obtained by multiplying the maximum allowable force with the maximum allowable offset of the force.
Transducers can be used to measure forces and moments in linkages such as those found in a robotic arm, where the links are connected by joints, and the magnitude and offset of the forces transmitted by these joints are used to control the linkage. In such applications, it is desirable to have a transducer which has significantly higher moment capacity than those available in the market. Accordingly, there is a need for an improved multi-component, low profile load transducer with high moment capacity.
When conventional load transducers are utilized in conjunction with force plates, unique load transducers must be designed and fabricated for force plates having a particular footprint size. Consequently, in order to fit force plates with varying footprint sizes, many different custom load transducers are required. These custom load transducers significantly increase the material costs associated with the fabrication of a force plate. Also, conventional load transducers often span the full length or width of the force plate component to which they are mounted, thereby resulting in elongate load transducers that utilize an excessive amount of stock material.
Therefore, what is needed is a load transducer that is capable of being interchangeably used with a myriad of different force plate sizes so that load transducers that are specifically tailored for a particular force plate size are unnecessary. Moreover, there is a need for a universal load transducer that is compact and uses less stock material than conventional load transducers, thereby resulting in lower material costs. Furthermore, there is a need for a force measurement assembly that utilizes the compact and universal load transducer thereon so as to result in a more lightweight and portable force measurement assembly.